Accretion definition, an increase by natural growth or by gradual external addition; growth in size or extent. See more.
Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and bloodstream. Learn more about how they function and quiz your knowledge at the end.
Respiratory System. The oxygen exchange in the lungs takes place across the membranes of small balloon-like structures called alveoli attached to the branches of the bronchial passages.These alveoli inflate and deflate with inhalation and exhalation. The behavior of the alveoli is largely dictated by LaPlace's law and surface tension.espiratory System. The oxygen exchange in the lungs takes place across the membranes of small balloon-like structures called alveoli attached to the branches of the bronchial passages.